The Large sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of stars, galaxies and QSOs. Objects in both the pilot survey and the first year regular survey are included in the LAMOST DR1. The pilot survey started in October 2011 and ended in June 2012, and the data have been released to the public as the LAMOST Pilot Data Release in August 2012. The regular survey started in September 2012, and completed its first year of operation in June 2013. The LAMOST DR1 includes a total of 1202 plates containing 2 955 336 spectra, of which 1 790 879 spectra have observed signalto-noise ratio (SNR) ≥ 10. All data with SNR ≥ 2 are formally released as LAMOST DR1 under the LAMOST data policy. This data release contains a total of 2 204 696 spectra, of which 1 944 329 are stellar spectra, 12 082 are galaxy spectra and 5017 are quasars. The DR1 not only includes spectra, but also three stellar catalogs with measured parameters: late A,FGK-type stars with high quality spectra (1 061 918 entries), A-type stars (100 073 entries), and M-type stars (121 522 entries). This paper introduces the survey design, the observational and instrumental limitations, data reduction and analysis, and some caveats. A description of the FITS structure of spectral files and parameter catalogs is also provided.

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Abstract. The BL Lacertae object AO 0235+16 is well known for its extreme optical and radio variability. New optical and radio data have been collected in the last four years by a wide international collaboration, which confirm the intense activity of this source: on the long term, overall variations of 5 mag in the R band and up to a factor 18 in the radio fluxes were detected, while short-term variability up to 0.5 mag in a few hours and 1.3 mag in one day was observed in the optical band. The optical data also include the results of the Whole Earth Blazar Telescope (WEBT) first-light campaign organized in November 1997, involving a dozen optical observatories. The optical spectrum is observed to basically steepen when the source gets fainter. We have investigated the existence of typical variability time scales and of possible correlations between the optical and radio emissions by means of visual inspection and Discrete Correlation Function (DCF) analysis. On the long term, the autocorrelation function of the optical data shows a double-peaked maximum at 4100-4200 days (11.2-11.5 years), while a double-peaked maximum at 3900-4200 days (10.7-11.5 years) is visible in the radio autocorrelation functions. The existence of this similar characteristic time scale of variability in the two bands is by itself an indication of optical-radio correlation. A further analysis by means of Discrete Fourier Transform (DFT) technique and folded light curves reveals that the major radio outbursts repeat quasi-regularly with a periodicity of ∼5.7 years, i.e. half the above time scale. This period is also in agreement with the occurrence of some of the major optical outbursts, but not all of them. Visual inspection and DCF analysis of the optical and radio light curves then reveal that in some cases optical outbursts seem to be simultaneous with radio ones, but in other cases they lead the radio events. Moreover, a deep inspection of the radio light curves suggests that in at least two occasions (the 1992-1993 and 1998 outbursts) flux variations at the higher frequencies may have led those at the lower ones.

We use a recently released SDSS catalog of X-ray emitting AGNs in conjunction with the FIRST 20cm radio survey to investigate the black hole fundamental plane relationship between the 1.4GHz radio luminosity (L r ), 0.1-2.4 keV X-ray luminosity (L X ), and the black hole mass (M), namely, logL r = ξ RX logL X +ξ RM logM +const. For this purpose, we have compiled a large sample of 725 broad-line AGNs, which consists of 498 radio-loud sources and 227 radioquiet sources. Our results are generally consistent with those in our previous work based on a smaller sample of 115 SDSS AGNs. We confirm that radio-loud objects have a steeper slope (ξ RX ) in the radio-X-ray relationship with respect to radio-quiet objects, and the dependence of the black hole fundamental plane on the black hole mass (ξ RM ) is weak. We also find a tight correlation with a similar slope between the soft X-ray luminosity and broad emission line luminosity for both radio-loud and radio-quiet AGNs, which implies that their soft X-ray emission is unbeamed and probably related to the accretion process. With the current larger sample of AGNs, we are able to study the redshift evolution of the black hole fundamental plane relation for both radio-loud and radio-quiet subsamples. We find that there is no clear evidence of evolution for radio-quiet AGNs, while for radio-loud ones there is a weak trend where ξ RM decreases as the redshift increases. This may be understood in part as due to the observed evolution of the radio spectral index as a function of redshift. Finally, we discuss the relativistic beaming effect and some other uncertainties related to the black hole fundamental plane. We conclude that, although introducing scatters to the fundamental plane relation, Doppler boosting alone is not enough to explain the observed steeper value of ξ RX in the radio-loud subsample with respect to the radio-quiet ones. Therefore, the significant difference of ξ RX between radio-loud and radio-quiet sources is probably also due to the different physical properties of the jets.

The activity of active galaxies may be triggered by the merging of galaxies, and present‐day galaxies are probably the product of successive minor mergers. The frequent galactic mergers at high redshift imply that active galaxies harbour supermassive unequal‐mass binary black holes at their centre at least once during their lifetime. The secondary black hole interacts and becomes coplanar with the accretion disc around the primary, inwardly spiraling toward their mass centre owing to the loss of orbital angular momentum to the disc mass outside the orbit of the secondary and/or to gravitational radiation. The binary black holes finally merge and form a more massive (post‐merged) black hole at the centre. In this paper it is shown that the recently‐discovered double‐lobed FR II radio galaxies are the remnants of such supermassive binary black holes. The inwardly spiraling secondary black hole opens a gap in the accretion disc that increases with time when the loss of the orbital angular momentum via gravitational radiation becomes dominant. When the supermassive black holes merge, the inner accretion disc disappears and the gap becomes a big hole of several hundreds of Schwarzschild radii in the vicinity of the post‐merged supermassive black hole, leading to an interruption of jet formation. When the outer accretion disc slowly refills the big hole on a viscous time‐scale, jet formation restarts and the interaction of the recurrent jets and the inter‐galactic medium forms a secondary pair of lobes. The model is applied to a particular double‐lobed radio source – B1834+620 – which has an interruption time‐scale ∼1 Myr. It is shown that the orbit of the secondary in B1834+620 is elliptical with a typical eccentricity e≃ 0.68 and that the ratio q of the mass of the secondary to that of the primary is 0.01 ≲q≲ 0.4. The accretion disc is a standard α‐disc with 0.01 ≲α≲ 0.04 and the ratio of disc half height H to radius r is δ≃ 0.01. The model predicts that double‐lobed radio structures form only in FR II or borderline FR I/FR II radio galaxies and that the detection rate of double‐lobed radio sources among FR II radio sources is about one per cent.